Phylogenetic analysis of ubiquitin-conjugating enzyme E2s in different insect orders. Amino acid sequences were aligned using ClustalW (www.ebi.ac.uk/clustalW), and a maximum likelihood tree was generated using MEGA 7.0. Nodes with distance bootstrap values (100 replicates) are shown. Different species are marked in different colors. Red dots indicate E2s in L. striatellus. Abbreviations: Zne, Zootermopsis nevadensis; Lstr, Laodelphax striatellus; Nlu, Nilaparvata lugens; Api, Acyrthosiphon pisum; Tca, Tribolium castaneum; Ame, Apis melifera; Dme, Drosophila melanogaster; Bmo, Bombyx mori.